Three graduate students in the MU College of Veterinary Medicine Department of Biomedical Sciences recently received fellowships to support their research projects. The American Heart Association awarded a predoctoral fellowship to Greg Ruegsegger and a postdoctoral fellowship to T. Dylan Olver. Jessica Hiemstra received the Ruth L. Kirschstein Institutional National Research Service Award from the National Institutes of Health National Heart, Lung, and Blood Institute.
Hiemstra earned a bachelor of science in animal science at Michigan State University and worked in animal research for several years. She came to MU three years ago to pursue a doctorate in biomedical sciences. She said she was attracted to Mizzou because of the university’s reputation as a leader in cardiovascular research.
The NIH grant will fund a research project she began in August under the mentorship of Craig Emter, PhD, an assistant professor in the CVM Department of Biomedical Sciences, and Tim Domeier, PhD, assistant professor in the MU School of Medicine Department of Medical Pharmacology and Physiology. Hiemstra is investigating heart failure with preserved ejection fraction, which occurs when the heart contracts normally, but the ventricles do not relax correctly as they refill with blood. Her study focuses on the role hormones play in that process.
“Women are more likely to experience heart failure after menopause, but we don’t know why,” she said.
Because pigs have a cardiovascular physiology that is similar to humans, she is working with intact female and male miniature swine. She is comparing different groups of swine, those with and without heart failure and those with and without hormones, to determine if sex hormones are protective.
Ruegsegger earned bachelor degrees in exercise physiology and biochemistry at Montana State University before coming to MU 2 ½ years ago to pursue a doctorate. Ruegsegger is looking into which genes may drive differences in behavior and lead to laziness. His research mentor is Frank Booth, PhD, a professor in the CVM Department of Biomedical Sciences, School of Medicine Departments of Medical Pharmacology and Physiology and Nutrition and Exercise Physiology, as well as a research investigator at the Dalton Cardiovascular Research Center.
“More than 90 percent of Americans don’t get the recommended amount of activity, and this leads to a lot of health problems,” Ruegsegger said.
The American Heart Association fellowship will allow Ruegsegger to continue his work with rats that have been bred to be extremely active or sedentary. Ruegsegger said he determined varying levels of naturally produced dopamine and opioids, which are pleasure-inducing chemicals, exist in the different groups of rats. Using chemicals, Ruegsegger blocks the receptors in the rats’ brains that are acted on by dopamine and opioids to study whether the rats’ activity level is affected.
Ruegsegger said his goal is to help prevent the onset of diseases caused by sedentary lifestyles by learning how molecules and receptors can make exercise more enjoyable.
Dylan Olver, PhD
Olver earned his doctoral degree in integrative physiology at the University of Western Ontario. His dissertation studies focused on how blood flow is controlled in peripheral nervous tissue and how microvascular function affects overall neural health in a diabetic setting with and without an exercise treatment intervention.
Olver has been at Mizzou for 1 ½ years. Working in Emter’s lab and that of M. Harold Laughlin, PhD, professor in the Department of Biomedical Sciences, he is studying the relationship between blood flow control in the brain and cognitive function. The American Heart Association grant will fund his research comparing the effects of interval training versus continuous training on blood vessels supplying the brain in pigs with heart failure.
For the study Olver created a cognitive testing scheme involving a spatial hole board task. He teaches healthy swine and swine with heart failure where to find food rewards in the hole board while monitoring how long it takes them to learn where the food is hidden. He then introduces a novel paradigm for the animals to overcome as they search for the hidden treats.
“Some pigs are very strategic, while others search randomly, which leads to short-term memory errors,” Olver noted.
Swine that have heart failure have stiffer arteries, which compromises blood flow to their brains and potentially impairs their cognitive function, Olver said.
“In the pigs with heart failure that exercised, we saw those vascular issues reversed and improved cognitive abilities. Now we want to look at what genes or vasoactive agents cause this. Our working hypothesis is that in pigs with heart failure, their sympathetic nervous system may be overactive causing vasoconstriction in the arteries supplying the brain. How does exercise circumvent that and can we determine the optimal therapeutic dose?” he said.
The grant will fund the study for two years.